a smoked herring.

something intended to divert attention from the real problem or matter at hand; a misleading clue.

Also called red-herring prospectus. Finance . a tentative prospectus circulated by the underwriters of a new issue of stocks or bonds that is pending approval by the U.S. Securities and Exchange Commission

so called because the front cover of such a prospectus must carry a special notice printed in red.

any similar tentative financial prospectus, as one concerning a pending or proposed sale of cooperative or condominium apartments.

noun

attention-grabber , bait , commotion , curve ball , deviation , distraction , distractor , disturbance , diversion , diversionary tactic , false clue , false face , false trail , fool\'s errand , gimmick , interruption , maneuver , ploy , smoke screen , wild-goose chase *